Aluminum — one of the major non-ferrous metals taking the leading positions among non-ferrous and other metals on release and consumption. This metal is widely applied in the form of alloys and in pure form in various industries.
Raw materials for industrial production of aluminum
Depending on the used raw materials and on a way of production aluminum is divided into groups:
- primary;
- secondary. Primary aluminum is produced from the mineral ores containing oxide of aluminum and differing with structure and its concentration. Aluminum oxide content in minerals:
- bauxites. The main aluminum ore containing up to 50% of oxide of aluminum; - nephelines (up to 30%);-alumstones (up to 20%).
For production of secondary aluminum and alloys also the scrap (carving and a trimming of sheets, pipes and tapes, a wire, a foil, current conductors, shaving and other waste) is used aluminum.
Production of primary aluminum
The production technology of metal aluminum from ore materials represents the difficult technological scheme consisting from several divisions, making: - alumina; - fluoric salts and cryolite; - coal products (lining blocks, electrodes); - electrolytic aluminum. The main elements of a technological chain are an alumina production (aluminum oxide) and electrolytic aluminum. The main method of industrial receiving aluminum is the method of electrolysis of aluminous fusion in cryolite. Electrolytic restoration of aluminum is an energy-intensive production therefore aluminum plants are located in areas with hydroelectric power station (cheap electric power), and alumina productions — near fields of aluminum ore. As the main device for receiving aluminum serves the aluminum bathtub or the electrolyzer. In the course of electrolysis the aluminum having higher density, than cryolite separates from fusion of a kriolitoglinozem and falls by a bathtub bottom where it gathers and taken by means of siphons or vacuum ladles which are sucking in aluminum through the pipe entered through an electrolyte layer into liquid aluminum. After that aluminum is purified (chlorinate) and cast in ingots. Aluminum of high purity is produced by additional refinement (to 99.99% of purity) or by means of subconnections (up to 99.9995% of purity).
Smelting of secondary aluminum
Secondary aluminum with necessary characteristics is received by smelting of aluminum scrap and waste in special furnaces with fuel or electric ways of melting. Before melting the waste sorts and subjects to cold processing (cutting) for removal of metal and nonmetallic impurity. Then scrap is given in directly to aluminum fusion in the bathing furnace with compulsory immersion in it for prevention of oxidation. Pouring of a ready-made product is made in foundry Chushka Spit of various form and other cast products.